body {
    background: #1e1e1e;
    font-family: Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.calculator {
    background: #2c2c2c;
    padding: 20px;
    border-radius: 12px;
    width: 300px;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.4);
    margin-bottom: 120px; /* add space for the advert-bottom */
}


.display {
    background: #000;
    color: #0aff0a;
    font-size: 32px;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 10px;
    text-align: right;
    overflow: hidden;
    white-space: nowrap;
}

button {
    width: 55px;
    height: 55px;
    margin: 5px;
    font-size: 20px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    background: #3d3d3d;
    color: #fff;
    transition: background 0.15s;
}

button:hover {
    background: #505050;
}

button:active {
    background: #666;
}

.button0 {
    width: 118px;
}

.buttonequals {
    background: #ff9500;
    color: white;
    width: 55px;
}

.buttonequals:hover {
    background: #e68600;
}

.buttonequals:active {
    background: #cc7700;
}
.advert-bottom {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background: #333;
    color: white;
    text-align: center;
    padding: 15px 0;
    border-top: 3px solid #0078ff;
    z-index: 9999;
}

.advert-bottom p {
    margin: 0 0 10px 0;
    font-size: 16px;
}

.ad-button-flash {
    margin-top: 15px;
    width: 100%; /* makes it full width like other buttons */
    background-color: #ff0000;
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    animation: flash 1s infinite;
}

@keyframes flash {
    0% { background-color: #ff0000; color: white; }
    50% { background-color: yellow; color: black; }
    100% { background-color: #ff0000; color: white; }
}

.ad-button-flash:hover {
    transform: scale(1.1);
}
.snow {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none; /* allows clicks through snow */
    overflow: hidden;
    z-index: 999; /* on top of everything */
}

.snowflake {
    position: absolute;
    color: white;
    font-size: 1em;
    user-select: none;
    pointer-events: none;
    animation-name: fall;
    animation-timing-function: linear;
}

@keyframes fall {
    0% {
        transform: translateY(-10%) rotate(0deg);
        opacity: 0;
    }
    10% {
        opacity: 1;
    }
    100% {
        transform: translateY(110vh) rotate(360deg);
        opacity: 0.8;
    }
}